The semiconductor industry has progressed into nanometer technology process nodes in pursuit of higher device density, higher performance, and lower cost. Despite groundbreaking advances in materials and fabrication, scaling planar device such as the conventional MOSFET has proven challenging. To overcome these challenges, circuit designers are looking to novel structures to deliver improved performance. One avenue of inquiry is the development of three-dimensional designs, such as a fin-like field effect transistor (FinFET). A FinFET can be thought of as a typical planar device extruded out of a substrate and into the gate. A typical FinFET is fabricated with a thin “fin” (or fin structure) extending up from a substrate. The channel of the FET is formed in this vertical fin, and a gate is provided over (e.g., wrapping around) the channel region of the fin. Wrapping the gate around the fin increases the contact area between the channel region and the gate and allows the gate to control the channel from multiple sides. This can be leveraged in a number of way, and in some applications, FinFETs provide reduced short channel effects, reduced leakage, and higher current flow. In other words, they may be faster, smaller, and more efficient than planar devices.
However, FinFETs and other nonplanar devices are developing technologies, meaning that in many aspects, their full potential has not yet been realized. As merely one example, channel strain (internalized pressure within a channel region) has been used in planar devices to improve the flow of charge carriers through the channel region. However, in nonplanar devices, it has proven much more difficult to generate channel strain, and when channel strain is produced, it has proven difficult to obtain the expected improved carrier mobility. Accordingly, while conventional techniques for forming a strained channel within a nonplanar device have been adequate in some respects, they have been less than satisfactory in others. In order to continue to meet ever-increasing design requirements, further advances are needed in this area and others.